In recent years, as an environmentally friendly vehicle, a vehicle that has an electric power storage device (for example a secondary battery, a capacitor, or the like) mounted therein and travels using a driving force produced from electric power stored in the electric power storage device is attracting attention. This vehicle includes an electric vehicle, a hybrid vehicle, a fuel-cell vehicle, and the like for example.
Such an electric power storage device is generally configured of a plurality of battery cells stacked in series or in parallel to output desired voltage. When these battery cells have disconnection, short circuit or similar defects, the electric power storage device may not normally function. Accordingly, detecting whether the battery cells have defect is required.
Japanese Patent Laying-Open No. 2009-227078 (PTL 1) discloses that a motive power system which employs a boost converter to boost voltage received from a battery and supplies the boosted voltage to an inverter and employs a DC-DC converter to lower the voltage of the battery and supplies the lowered voltage to accessories, uses a voltage value received from a first voltage sensor that senses a voltage of the boost converter at a side where the battery is connected and a voltage value received from a second voltage sensor that senses a voltage of the DC-DC converter at a side where the battery is connected to determine whether the first voltage sensor has defect and whether the battery has overvoltage fault.